000 AXNT20 KNHC 092353 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN AUG 09 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... A TROPICAL WAVE IS ALONG 23W FROM 6N TO 18N MOVING W NEAR 15 KT. ASSOCIATED LOW PRES 1009 MB IS LOCATED ALONG THE WAVE AXIS NEAR 14N. LATEST SATELLITE IMAGERY INDICATES A WELL DEFINED LOW/MID LEVEL CYCLONIC CIRCULATION WITH A CLUSTER OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION FLARING UP NEAR THE LOW LEVEL CIRCULATION...AND AN ADDITIONAL BAND OF SCATTERED MODERATE CONVECTION WITHIN 90 NM EITHER SIDE OF A LINE THROUGH 13N22W TO 9N25W. THERE IS A MEDIUM PROBABILITY OF TROPICAL CYCLONE FORMATION WITH THIS WAVE AND LOW OVER THE NEXT 48 HOURS. REFER TO THE TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR ADDITIONAL DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS TILTED NW TO SE FROM 19N45W TO 6N38W MOVING W NEAR 20 KT. THE AXIS OF THE WAVE IS ORIENTED WITHIN A MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. A LINE OF ISOLATED MODERATE CONVECTION IS WITHIN 30 NM OF A LINE FROM 15N35W TO 15N41W. ALSO...SCATTERED MODERATE CONVECTION IS IN CLOSER PROXIMITY TO THE ITCZ AXIS FROM 6N-9N BETWEEN 36W-43W. A TROPICAL WAVE PREVIOUSLY ALONG 48W HAS BEEN REPOSITIONED FARTHER W AND IS LOCATED ALONG 55W FROM 8N TO 19N MOVING W NEAR 12 KT. THIS WAVE APPEARS TO HAVE BEEN ABSORBED BY A SURFACE TROUGH THAT HAD BEEN LOCATED IMMEDIATELY W OF THE WAVE AXIS OVER THE PAST COUPLE OF DAYS. CONFIRMATION OF THE NEW POSITION OF THE WAVE IS BASED ON A MOISTURE MAXIMUM OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. ALSO LOW-LEVEL CYCLONIC CIRCULATION IS EVIDENT IN THE LOW-LEVEL CLOUD FIELD ALONG THE WAVE AXIS NEAR 14N. SCATTERED SHOWERS ARE FROM 14N-17N BETWEEN 53W-58W. A TROPICAL WAVE IS ALONG 66W S OF 16N MOVING W NEAR 20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF MODERATE ELY TRADES OVER THE ERN CARIBBEAN AND COINCIDES WITH A MAXIMUM OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS ARE LOCATED ACROSS THE SE CARIBBEAN S OF 14N BETWEEN THE LESSER ANTILLES AND 70W. A TROPICAL WAVE IS ALONG 87W S OF 17N MOVING W NEAR 15 KT. WAVE REMAINS RATHER ILL-DEFINED ON SATELLITE IMAGERY AS IT MOVES ACROSS HONDURAS AND EL SALVADOR. NO ASSOCIATED DEEP CONVECTION IS NOTED WITH THE WAVE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N27W 9N38W 8N41W 13N54W 13N57W 11N65W. APART FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED SHOWERS ARE FROM 6N-10N BETWEEN 28W-36W. FARTHER TO THE W...SCATTERED MODERATE CONVECTION IS FROM 12N-15N BETWEEN 58W-64W AND MOVING ACROSS THE WINDWARD ISLAND. ...DISCUSSION... GULF OF MEXICO... AMPLIFIED PATTERN IN PLACE OVER THE CONUS WITH AN UPPER RIDGE AND ASSOCIATED ANTICYCLONE ANCHORED OVER SOUTH CAROLINA WITH AN EXTENSION OF THE RIDGE INTO THE GULF OF MEXICO TO NEAR 20N96W. A SURGE OF DRY AIR ALOFT IS SWEEPING ACROSS NRN FLORIDA AND THE NE GULF N OF 27N CAPPING TSTM DEVELOPMENT OVER FLORIDA EXCEPT OVER THE FAR SW PORTION OF THE FLORIDA PENINSULA. ON THE BACKSIDE OF THE RIDGE AND EAST OF A TROUGH OVER MEXICO...SOUTHERLY FLOW ALOFT IS ADVECTING SIGNIFICANT DEEP LAYERED MOISTURE N ACROSS THE WRN GULF AND INLAND ACROSS E TEXAS AND LOUISIANA. SCATTERED SHOWERS AND TSTMS ARE N OF 24N W OF 88W. A MORE CONCENTRATED AREA OF SCATTERED SHOWERS AND TSTMS IS LOCATED OVER THE ERN BAY OF CAMPECHE AND SRN MEXICO DUE TO SURFACE WIND CONVERGENCE AND THE UPPER DIFFLUENT PATTERN IN PLACE. CARIBBEAN SEA... THE PERIPHERY OF AN UPPER RIDGE OVER THE SW NORTH ATLC EXTENDS ACROSS THE FAR NW CARIBBEAN AND YUCATAN PENINSULA. AS THE UPPER LEVEL RIDGE CONTINUES MOVING W...IN ITS WAKE AN UPPER LEVEL TROUGH EXTENDING FROM THE WINDWARD PASSAGE TO JUST OFF THE COAST OF NICARAGUA AND COSTA RICA WAS ADVANCING WWD AT 10-15 KT. VERY DRY AIR ALOFT WAS NOTED ACROSS THE WRN CARIBBEAN N OF 12N W OF 74W. FARTHER TO THE E...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE NRN LEEWARD ISLANDS TO 15N70W. DIFFLUENT SOUTH AND SELY FLOW OVER THE CARIBBEAN S OF THE RIDGE AXIS WAS AIDING IN THE DEVELOPMENT OF SCATTERED SHOWERS AND TSTMS ACROSS THE WINDWARD ISLANDS TO NEAR THE ABC ISLANDS. THIS ACTIVITY APPEARED TO BE ALIGNED WITH AN EXTENSION OF THE ITCZ FROM THE TROPICAL ATLC. A MORE CONCENTRATED AREA OF SCATTERED SHOWERS AND TSTMS IS OCCURRING OVER THE FAR SW CARIBBEAN S OF 12N BETWEEN 73W-86W... INCLUDING PANAMA...COSTA RICA AND SRN PORTIONS OF NICARAGUA. ATLANTIC OCEAN... AN UPPER RIDGE/ANTICYCLONE OVER SOUTH CAROLINA GOVERNS THE PATTERN OVER THE FAR NW PORTION OF THE SUBTROPICAL ATLC WITH DRY AIR ALOFT SUPPRESSING MOST TSTM ACTIVITY. HOWEVER...A NARROW UPPER TROUGH EXTENDS FROM THE WINDWARD PASSAGE NE TO BEYOND 32N57W. A LARGE AREA OF UPPER LEVEL DIFFLUENT FLOW EXISTS BETWEEN THE RIDGE AND TROUGH AND IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS ALONG AND S OF A SURFACE TROUGH WHICH EXTENDS FROM 31N63W TO 28N73W. AN UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM 32N44W TO 27N50W. A SURFACE TROUGH THAT HAS DRIFTED WWD OVER THE PAST 24 HOURS EXTENDS FROM 24N57W TO 29N54W AND WILL CONTINUE WEAKENING AS THIS UPPER LEVEL SUPPORT MOVES OFF TO THE NE. AN AMPLIFIED RIDGE EXTENDS FROM 32N33W TO AN ANTICYCLONE CENTERED NEAR 22N39W THEN CONTINUING SW TO NEAR 20N50W. A CHANNEL OF MODERATE TO STRONG NLY WINDS AND DRY AIR ALOFT IS SWEEPING SWD BETWEEN THE RIDGE AND AN UPPER LEVEL LOW S OF THE CANARY ISLANDS NEAR 26N18W. THIS FLOW MAY IMPACT THE POTENTIAL DEVELOPMENT OF THE LOW PRESSURE AREA NEAR 14N23W. THE REMAINDER OF THE ATLC REMAINS TRANQUIL WITH A BROAD AREA OF SAHARAN DUST COVERING MOST OF THE AREA E OF 45W. $$ HUFFMAN